Bug 1425: Failure when dragging a symlink to a directory between sessions

https://winscp.net/tracker/1425
(cherry picked from commit dea7eec66b3c2fe66c44ce51dc24fde741fd71f2)

Conflicts:
	source/forms/CustomScpExplorer.cpp

Source commit: 386888b26c8f6ec6a81914ad23aa121a9ebaaef2

source/forms/CustomScpExplorer.cpp

@@ -3477,12 +3477,15 @@ bool __fastcall TCustomScpExplorerForm::RemoteTransferFiles(
 
         TTerminalManager::Instance()->ActiveTerminal = Session;
 
-        TGUICopyParamType CopyParam = GUIConfiguration->CurrentCopyParam;
-        CopyParam.FileMask = FileMask;
+        if (TemporaryFilesList->Count > 0)
+        {
+          TGUICopyParamType CopyParam = GUIConfiguration->CurrentCopyParam;
+          CopyParam.FileMask = FileMask;
 
-        assert(!FAutoOperation);
-        FAutoOperation = true;
-        FTerminal->CopyToRemote(TemporaryFilesList, Target, &CopyParam, cpTemporary);
+          assert(!FAutoOperation);
+          FAutoOperation = true;
+          FTerminal->CopyToRemote(TemporaryFilesList, Target, &CopyParam, cpTemporary);
+        }
       }
       __finally
       {